Prosthetic hand with overload release means and means for adjusting relative finger and thumb positions



July 5, 1966 N. J. BROWN 3,258,784

PROSTHETIC HAND WITH OVERLOAD RELEASE MEANS AND MEANS FOR ADJUSTING RELATIVE FINGER AND THUMB POSITIONS Filed Aug. 5, 1963 2 Sheets-Sheet 1 INVENTOR. NOEL J. BROWN A 7' TORNEVS y 5, 1966 N. J. BROWN 3,258,784

PROSTHETIC HAND WITH OVERLOAD RELEASE MEANS AND MEANS FOR ADJUSTING RELATIVE FINGER AND THUMB POSITIONS Filed Aug. 5, 1963 2 Sheets-Sheet 2 NOEL J. BROWN madam?- A 7' TORNEVS United States Patent Oil ice 3,258,784 Patented July 5, 1966 3,258 7 84 PROSTHETIC HAND WITII OVERLOAD RELEASE MEANS AND MEANS FOR ADJUSTING RELA- TIVE FINGER AND THUMB POSITIONS Noe] J. Brown, 541 Division Ave., Campbell, Calif. Filed Aug. 5, 1963, Ser. No. 299,734 8 Claims. (Cl. 3-12.7)

This invention relates to improvements in prosthetic hands in general. More particularly, this invention relates to an improved prosthetic hand in which the closing position of the fingers and thumb of the prosthetic hand is adjustable.

An object of this invention is to provide an improved prosthetic hand with which a firm grip may be obtained on an object that the wearer desires to handle and in which the force required to release this grip is adjustable.

Another object of this invention is to provide an improved prosthetic hand in which the thumb and selected fingers thereof are pivoted to the frame of the hand and in which these pivoted members are connected to a crank type lever which is spring biased to bring it past dead center of the pivot of the crank when the pivoted thumb and pivoted fingers are closed, the crank type lever being pivotally supported on the hand frame by means of a pivot the position of which is adjustable with reference to the hand frame whereby the pivoted fingers and thumb may be adjusted so that the tips thereof just touch when the fingers and thumb are closed.

Still another object of this invention is to provide an improved prosthetic hand with selected fingers thereof pivoted to the frame of the hand, said fingers being movable on their pivots by means of a crank type lever which is connected thereto and which is pivotally supported on the hand frame by means of a yieldable bracket which is adapted to shift when a predetermined force exerted on said fingers is exceeded so that the article gripped by said fingers may be released without damage to the amputee or to the prosthetic hand.

Other and further objects of this invention will be apparent to those skilled in the art to which it relates from the following specification, claims, and drawings in which, briefly:

FIG. 1 is a view in side elevation of a hand embodying this invention, the positions of the thumb and forefinger of the prosthetic hand being shown in closed position in solid lines and in open position in broken lines;

FIG. 2 is a view of the back of the prosthetic hand partially broken away to show the internal mechanism;

FIG. 3 is a sectional view taken along the line 33 of FIG. 2 showing the pivot pin and operating lever of one of the pivotally supported fingers of this prosthetic hand, the fragmentary finger being shown in grippingposition in solid lines and in open position in broken lines;

FIG. 4 is a fragmentary sectional view taken along the line 44 of FIG. 2, the fragmentary finger being shown in closed position in solid lines and in open position in broken lines;

FIG. 5 is a view similar to FIG. 2 except that in FIG. 5 the internal mechanism of this prosthetic hand is illustrated with the parts thereof having been operated to open the pivoted fingers and thumb of the hand;

FIG. 6 is a detail view showing the crank supporting bracket in one position in solid lines and in a deflected position in broken lines;

FIG. 7 is a fragmentary sectional view taken along the line 7-7 of FIG. 5 showing the operating linkage for moving the thumb of this prosthetic hand on its pivot;

FIG. 8 is a fragmentary sectional view taken along the line 88 of FIG. 5; and

linkage between the fingers and the operating lever associated therewith.

This prosthetic hand is an improvement over the device shown in my Patent No. 3,026,534, issued on March 27, 1962. Referring to the drawings in detail, there is shown in FIGS. 2 and 5 a frame member 10 of the artificial hand made in simulation of the metacarpus of a human hand having a thumb 11 and fingers 12, 13, 14 and 15 and being provided with a flexible covering 10a made of rubber, plastic or the like finished to appear like a human hand. Frame 10 has a chamber 25 formed therein and this frame is made of metal such as aluminum or magnesium or alloys thereof to provide a light and strong construction. A shank 16, shown in FIG. 1, is attached in rigid fashion to the back wall 18 of the frame and this shank is provided for attachment of the prosthetic hand to a member retained upon the arm or shoulder of the wearer. A suitable metal disc and a rubber gasket (not shown) are provided around the shank 16.

A cable 17 for actuating the lever 19 is attached to the clevis 21 which is in turn pivotally attached by the pivot pin 22 to one end of the lever 19. The other end of this lever is pivotally attached by means of the pivot pin 23 to the inner wall of frame 10, as shown in FIGS. 2, 5 and 7. The end of the lever 19 that is attached to the hand frame by the pin 23 and the middle portion of said lever that is attached to the lever 27 by pin 26 are bifurcated, as shown in FIG. 7, so as to provide a stronger and more eflicient mechanism. The middle bifurcated portion of lever 19 is provided with holes for receiving the pivot pin 26 which is used for pivotally attaching the upper end of lever 27 thereto.

The lower end of the lever 27 is pivotally attached to the crank 29 by means of the pivot pin 28, as shown in FIGS. 2, 5 and 6. The crank 29 is made of a relatively thick plate as shown in FIG. 8. The central part of this crank is milled out so that the levers 27 and 33, which are attached to this crank 29 by means of the pivot pins 28 and 31, respectively, may be positioned therein, as shown in FIG. 8. The lever 33 which is attached to the crank 29 by means of the pivot pin 31 is positioned partly in the milled out part of the crank 29, and this lever is cut away on one side thereof as shown at 33a in FIG. 2 so that when the fingers of the hand are closed this lever just clears the crank supporting pin 30.

The crank 29 is pivotally attached by the pivot pin 30 to the bracket 32. The bracket arrangement for support ing the crank 29 includes the forked member 32' and the plate member 32a which is of resilient material such as beryllium-copper alloy or the like. Plate member 32a is attached to the member 32 by the small machine screws 320, as shown in FIG. 2, and it is also attached to the wall 18 of frame member 10 by the small machine screws 32b. A small set screw 32d is threaded into the back wall 18 of the frame and this screw is employed for adjusting the position of the bracket arrangement as shown in FIG. 6, and it thus forms an adjustment whereby the fingers 1-2 and 13 and thumb 11 may be adjusted so that the tips thereof just touch when the hand is closed. In FIG. 6 the bracket 32 is shown in solid lines when the screw 32d is fully retracted. Thus by advancing the set screw 32d against the plate 32a the bracket arrangement is tilted into the position shown in broken lines, with the result that the position of the pivot pin 30 is shifted from the position shown in solid lines toward that shown in broken lines. Generally, only a small adjustment of the screw 32d is necessary.

The fingers 12 and 13 are provided with small recesses 12a and 13a at the roots thereof for receiving the projections 36 and 37 which are formed integral with the frame 10, as shown in FIG. 6. These fingers 12 and 13 are pivotally attached to the projections 36 and 37, respecti vely, by means of the pins 38 and 39, respectively.

The lever 33 is connected to the fingers 112 and 13 by the pin 35 and the ball members 33a, 12a and 13a as shown in FIG. 9. These ball members are provided with holes through the centers thereof and the pin 35 extends through these holes. Thus the ball members 12a and 13a which are positioned in suitable sockets or recesses formed in the fingers 12 and 13 respectively are positioned on opposite sides of the ball member 33a which is positioned in a hole or recess formed in the lever 33. After the ball members 12a and 13a are placed in the recesses, a small amount of the metal around the edges of these recesses is staked or peened thereover to prevent the ball members from leaving the recesses but at the same time permit some rotative or turning motion thereof in the recesses. This rotative or turning motion is limited by the end portion of the pin 35 that is positioned in the recess 13b formed in the finger 13. This recess is made somewhat larger than the pin so that the pin may move therein a limited amount before it engages the sides of the recess and as a result the Wobble of fingers 12 and 13 with respect to each other is limited.

A suitable recess is also provided in the lever 33 for receiving the ball member 33a and after this ball memher is placed in this recess the edges of the recess around the ball member are staked or peened over it to prevent the ball member from being removed therefrom. This swivel connection between the lever 33 and the fingers 12 and 13 provides for actuation of the fingers 12 and 13 by the leverage shown in FIGS. 2 and even though the pivot pins 38 and 39 for these fingers are not parallel and also as the lever 33 undergoes a certain amount of rotation in its up and down movement.

When the lever 33 is moved upward, the fingers are moved from their closed position, as is illustrated in the case of finger 13 which is shown in solid lines in FIG. 3, to the open position which is shown in the case of finger '13 in broken outline in the same figure. The inner extension of the thumb 11 is connected by means of the link 40 to the lever 33. The ends of the link 40 are provided with sockets for receiving the ball shaped heads of screw 41 and 42, respectively. Thus the screw 41 is provided with a nut 41a, as shown in FIGS. 2 and 5, for attaohing and holding this screw fastened to the lever 33, and screw 42 is attached to the inner extension of the thumb 11 by means of the nut 42a, as shown in FIG. 7. This link is employed for the purpose of shifting the thumb 11 to its opened position when the lever 33 is moved upward. It is of course possible to provide this prosthetic hand with only the fingers 12 and 13 pivotally attached and movable by the actuating mechanism and to provide a thumb 11 rigidly attached to the hand or vice versa, if desired.

The finger 14 is pivotally attached to the hand frame by the pin 14a as shown in FIG. 4 and it may be rotated around this pivot until the stop surface 14c or 14d thereof engage the frame 10 of the hand. This finger is provided with a recess 14b in the side thereof adjacent to finger 13 and this recess is adapted to receive the outer end of the pin 35a which is attached to the lower end of finger 13. Some play is provided in this recess 14b for the outer end of pin 35a so that this finger may be moved to a certain extent independently of the pin 35a or finger 13. Also the finger 13 may move through a certain angle before the pin 35a imparts r-otative motion to finger 14. The little finger is also pivotally attached to the hand frame. This pivotal attachment is quite free so that this little finger 15 may be moved on the hand through a certain angle depending on the stop surfaces provided to the bottom thereof which are similar to the stop surfaces provided to the bottom of finger 14. The outside covering of flexible plastic material, however, prevents loose flapping movement of these fingers 14 and 15.

When this prosthetic hand has the fingers 12 and 13 and thumb 11 in the closed position, as shown in the solid lines in FIG. 1, the mechanism is in the position shown in FIG. 2 with the actuating cable 17 thereof relaxed so that either the end of the lever 19 or the set screw 19a is in engagement with the frame 10. While the top of the lever 19 may abut the hand frame and thus provide a stop for the upward swing of this lever, it has been found that providing a set screw 19a in the lever 19 to function as a stop when it abuts the hand frame, is more desirable. The adjustable set screw 19a thus functions as a settable stop for limiting the rotation of the crank 29 in the clockwise direction produced by the pulling force of the spring 29a. This set screw can be adjusted after the hand is assembled to provide the proper angular positioning of the pivot pin 31 with respect to pin 30. It also provides an adjustment that may be used to compensate for bearing Wear at the various pivot pins 23, 26, 28, 30 and 31 to keep the mechanism functioning properly even after a long period of use.

The plate 32a also provides a safety feature in this hand and for this purpose it is made so that the end portion thereof, that is attached to the bracket 32, will flex upward if the amputw wearing this hand attempts to lift too great a load. The hand will thus release its grip on the excessive load before harming the amputee or damaging the hand. When the plate 32a is flexed by excessive loading of the hand, it momentarily assumes the position shown in broken lines in FIG. 6 in which the lever 33 is unlocked and the fingers may be shifted to their open position.

While I have show a preferred embodiment of the invention it will be understood that the invention is capable of variation and modification from the form shown so that its scope should be limited only by the scope of the claims appended hereto.

What I claim is:

1. A prosthetic hand comprising a hollow frame forming a body of the prosthetic hand, a plurality of fingers including a thumb, means pivotally attaching a finger opposite said thumb to the forward end of said frame, means attaching said thumb to a side of said frame, and a mechanism normally holding said thumb and said pivotally mounted finger closed, said mechanism comprising a crank pivotally attached to the inside of said frame, a lever having one end pivotally connected to said crank, means pivotally connecting the other end of said lever to said pivotally mounted finger opposite said thumb, resilient means rotating said crank in one direction to close said thumb and said pivotally mounted finger and stop means for said crank for stopping the rotation of said crank by said resilient means when said thumb and said pivotally mounted finger are substantially closed, said stop means being positioned such that when it stops rotation of said crank said lever and said crank lock said thumb and said pivotally mounted finger in closed position, adjustable means mounting said crank on said frame, means for adjusting said mounting means for moving the tip of said pivotally mounted finger toward or away from the tip of said thumb, and means for rotating said crank in the opposite direction to move said pivotally mounted finger from said thumb.

2. A prosthetic hand comprising a hollow frame forming the body of the prosthetic hand, a plurality of fingers including a thumb, means pivotally attaching a finger opposite said thumb to the forward end of said frame, and a mechanism normally holding said pivotally mounted finger and said thumb closed, said mechanism comprising a crank pivotally atached to the inside of said frame, a lever having one end pivotally connected to said crank, means pivotally connecting the other end of said lever to said pivotally mounted finger opposite asid thumb, resilient means rotating said crank in one direction to close said pivotally mounted finger and said thumb, stop means for said crank for stopping the rotation of said crank by said resilient means when said thumb and said pivotally mounted finger are substantially closed, said stop means being positioned such that when it stops rotation of said crank said thumb and said pivotally mounted finger are locked in closed positron, said mechanism including means for mounting said crank on said frame including a flexible plate which flexes and releases said pivoted finger from the closed position if the wearer of the hand attempts to lift an excessive load, and means for rotating said crank in the opposite direction to open said thumb and said pivotally mounted finger.

3. A prosthetic hand comprising a hollow frame forming the body of the prosthetic hand, a plurality of fingers including a thumb, means pivotally attaching a finger opposite said thumb to the forward end of said frame, means attaching said thumb to a side of said frame, and a mechanism normally holding said thumb and said pivotally mounted finger closed, said mechanism comprising a crank, means for pivotally attaching said crank to the inside of said frame, said means including a flexible plate having one end position attached to said frame, a set screw in said frame for flexing said plate to adjust said pivotally attached finger, a lever having one end pivotally connected to said crank, means pivotally connecting the other end of said lever to said pivotally mounted finger opposite said thumb, resilient means rotating said crank in one direction to close said thumb and said pivotally mounted finger, stop means for said crank for stopping the rotation of said crank by said resilient means when said thumb and said pivotally mounted finger are substantially closed, said stop means being positioned such that when it stops rotation of said crank said thumb and said pivotally mounted finger are locked in closed position, and means for rotating said crank in the opposite direction to open said thumb and said pivotally mounted finger.

4. A prosthetic hand comprising a hollow frame forming the body of the prosthetic hand, a plurality of fingers including a thumb, means pivotally attaching a finger opposite said thumb to the forward end of said frame, means pivotally attaching said thumb to a side of said frame, said thumb having an extension extending into said frame past the pivot thereof, and a mechanism normally holding said thumb and said pivotally mounted finger closed, said mechanism comprising a crank, a bracket, means attaching said bracket to said frame, means pivotally attaching said crank to said bracket to the inside of said frame, a lever having one end pivotally connected to said crank, means pivotally connecting the other end of said lever to said pivotally mounted finger opposite said thumb and a linkage pivotally connecting the inner end portion of said thumb extension to a point of said lever intermediate the ends thereof, resilient means rotating said crank in one direction to close said thumb and said pivotally mounted finger, a second lever having one end pivotally attached to said frame, means for connecting an intermediate point of said second lever to said crank for rotating said crank, and stop means positioned on said second lever for engaging said frame and for stopping the rotation of said crank by said resilient means when said thumb and said pivotally mounted finger opposite said thumb are substantially closed, said stop means being adjustable so that it stops rotation of said crank when the pivot of said first mentioned lever on said crank is past dead center with respect to the pivot of said crank whereby said thumb and said pivotally mounted finger opposite said thumb are locked in closed position when said stop means arrests rotation of said crank, and means attached to the other end of said second lever fo rotating said crank in the opposite direction to open said thumb and said pivotally mounted finger.

5. A prosthetic hand comprising a hollow frame forming the body of the prosthetic hand, a plurality of fingers including a thumb, means pivotally attaching a finger opposite said thumb to the forward end of said frame, means pivotally attaching said thumb to a side of said frame, said thumb having an extension extending into said frame past the pivot thereof, and a mechanism normally holding said thumb and said pivotally mounted finger closed, said mechanism comprising a crank, a bracket, a flexible plate, means attaching said bracket to one end portion of said plate and means attaching the other end portion of said plate to said frame, means pivotally attaching said crank to said bracket, a lever having one end pivotally connected to said crank, means pivotally connecting the other end of said lever to said pivotally mounted finger opposite said thumb and a linkage pivotally connecting the inner end portion of said thumb extension to a point of said lever intermediate the ends thereof, means for flexing said plate to adjust the ends of said pivoted finger and said thumb toward or away from each other, resilient means rotating said crank in one direction to close said thumb and said pivotally mounted finger, a second lever having one end pivotally attached to said frame, means connecting an intermediate point of said second lever to said crank for rotating said crank, and stop means positioned on said second lever for engaging said frame and for stopping the rotation of said crank by said resilient means when said thumb and said pivotally mounted finger opposite said thumb are substantially closed, and means attached to the other end of said second lever for rotating said crank in the opposite direction to open said thumb and said pivotally mounted finger.

6. A prosthetic hand comprising a hollow frame forming the body of the prosthetic hand, a plurality of fingers including a thumb, means pivotally attaching the fingers opposite said thumb to the forward end of said frame, means pivotally attaching said thumb to a side of said frame, said thumb having an extension extending into said frame past the pivot thereof, and a mechanism normally holding said thumb and said pivotally mounted fingers closed, said mechanism comprising a crank, a bracket, a flexible plate, means attaching said bracket to one end portion of said plate and means attaching the other end portion of said plate to said frame, means pivotally attaching said crank to said bracket, a finger actuating lever having one end pivotally connected to said crank, means pivotally connecting the other end of said finger actuating lever to said pivotally mounted fingers opposite said thumb and a linkage pivotally connecting the inner end portion of said thumb extension to a point of said lever intermediate the ends thereof, means for flexing said plate to adjust the ends of said pivoted fingers and said thumb toward or away from each other, resilient means rotating said crank in one direction to close said thumb and said pivotally mounted fingers, a second lever having one end pivotally attached to said frame, means connecting an intermediate point of said second lever to said crank for rotating said crank, and stop means positioned on said second lever for engaging said frame and for stopping the rotation of said crank "by said resilient means when said thumb and said pivotally mounted fingers are substantially closed, said stop means being adjustable so that it stops rotation of said crank when the pivot of said first mentioned lever on said crank is past dead center with respect to the pivot of said crank whereby said thumb and said pivotally mounted fingers are locked in closed position when said stop means arrests rotation of said crank, and means attached to the other end of said second lever for rotating said crank in the opposite direction to open said thumb and said pivotally mounted fingers.

7. A prosthetic hand as set forth in claim 6 further comprising means for pivotally attaching an additional finger adjacent to said pivotally attached fingers to said frame, said additional finger having a recess near the attached end thereof, said first mentioned pivotally attached fingers having a pin fixedly attached thereto, said pin extending into said recess of said additional finger so that said additional finger is tilted on its pivot by said pin when said first mentioned pivotally attached finger is moved to a predetermined extent.

8. A prosthetic hand as set forth in claim 6 further characterised in that said means pivotally connecting said finger actuating lever to the pivotally mounted fingers includes a member extending between said pivotaily mounted fingers, ball means positioned in sockets formed in said pivotally mounted fingers, said member extending through holes formed through said ball means, said member extending into a recess formed in one of said fingers to limit the motion of said fingers independently of each other when said member engages said recess, and additional ball means on said member between said first mentioned ball means, said finger actuating lever having a recess for holding said additional ball means.

References Cited by the Examiner UNITED STATES PATENTS 3,026,534 3/1962 Brown 3-12.7

l0 RICHARD A. GAUDET, Primary Examiner.

R. L. FRINKS, Assistant Examiner. 

1. A PROSTHETIC HAND COMPRISING A HOLLOW FRAME FORMING A BODY OF THE PROSTHETIC HAND, A PLURALITY OF FINGERS INCLUDING A THUMB, MEANS PIVOTALLY ATTACHING A FINGER OPPOSITE SAID THUMB TO THE FORWARD END OF SAID FRAME, MEANS ATTACHING SAID THUMB TO A SIDE OF SAID FRAME, AND A MECHANISM NORMALLY HOLDING SAID THUMB AND SAID PIVOTALLY MOUNTED FINGER CLOSED, SAID MECHANISM COMPRISING A CRANK PIVOTALLY ATTACHED TO THE INSIDE OF SAID FRAME, A LEVER HAVING ONE END PIVOTALLY CONNECTED TO SAID CRANK, MEANS PIVOTALLY CONNECTING THE OTHER END OF SAID LEVER TO SAID PIVOTALLY MOUNTED FINGER OPPOSITE SAID THUMB, RESILIENT MEANS ROTATING SAID CRANK IN ONE DIRECTION TO CLOSE SAID THUMB AND SAID PIVOTALLY MOUNTED FINGER AND STOP MEANS FOR SAID CRANK FOR STOPPING THE ROTATION OF SAID CRANK BY SAID RESILIENT MEANS WHEN SAID THUMB AND SAID PIVOTALLY MOUNTED FINGER ARE SUBSTANTIALLY CLOSED, SAID STOP MEANS BEING POSITIONED SUCH THAT WHEN IT STOPS ROTATION OF SAID CRANK SAID LEVER AND SAID CRANK LOCK SAID THUMB AND SAID PIVOTALLY MOUNTED FINGER IN CLOSED POSITION, ADJUSTABLE MEANS MOUNTING SAID CRANK ON SAID FRAME, MEANS FOR ADJUSTING SAID MOUNTING MEANS FOR MOVING THE TIP OF SAID PIVOTALLY MOUNTED FINGER TOWARD OR AWAY FROM THE TIP OF SAID THUMB, AND MEANS FOR ROTATING SAID CRANK IN THE OPPOSITE DIRECTION TO MOVE SAID PIVOTALLY MOUNTED FINGER FROM SAID THUMB. 